Certain embodiments of the present invention generally relate to a strain relief for maintaining a secure connection between separate structures, such as between electrical cables, coaxial cables, connectors, circuit boards and the like, with little or no compressive force.
In the past, connectors have been proposed for connecting electrical cables that carry power and/or data signals with other cables or other structures. Generally, electrical cables have a particular cross-sectional geometry such as the circular geometry of a coaxial cable formed with a central conductor (of one or more conductive wires) surrounded by insulation or a cable dielectric material. In coaxial cables, the dielectric material is surrounded by a circular, ring-shaped outer conductor, such as a cable braid (of one or more conductive wires). The outer conductor is surrounded by a jacket.
In certain applications using coaxial cables, a connector is mounted on at least one end of the coaxial cable. The connector includes contacts that are electrically secured to center and outer conductors of the coaxial cable through various contact mounting means. The contact mounting means may include, among other things, a crimp, solder, set screws and the like. The connector mounted on the coaxial cable is typically plugged into a mating connector that is housed on an electrical system. The electrical system, into which the coaxial cable is plugged, may be moved with little concern for the attached coaxial cable. During installation and throughout use, coaxial cables are repeatedly bent and pulled. The bending and pulling forces tend to cause relative motion at the electrical interface between the connector and the cable conductor(s). It is desirable to limit the bending and pulling forces induced on the electrical interface in order to prevent relative movement between the connector and the cable and to prevent relative movement at a separable interface between mating contacts.
Strain reliefs have been proposed to limit the amount of movement within, and forces experienced on, the electrical interface between the connector and the cable. For example, conventional strain reliefs have been mounted to, or formed integral with, the connector. The strain relief extends outward from the connector along the cable proximate the point at which the coaxial cable joins the connector. The strain relief includes an arc-shaped section that receives the jacket of the coaxial cable. One or both ends of the arc-shaped section include crimp beams that fold over or wrap around the coaxial cable. The crimp beams are compressed to securely grip the jacket of the coaxial cable between the crimp beams and the arc-shaped section of the strain relief.
However, these conventional strain reliefs have experienced certain drawbacks. For example, when the strain relief compresses the jacket of a coaxial cable, the strain relief deforms the shape of the coaxial cable. Coaxial cables normally have a circular cross-section with a central conductor positioned at the center of the outer conductor which has a ring-shaped circular cross-section. The circular shape of the outer conductor and the relation between the center and outer conductors is maintained by the dielectric material that separates the center and outer conductors. It is preferable to maintain the circular shape for the outer conductor in order to maintain an even radial distance between the center and outer conductors. This even radial distance, in turn, maintains symmetric electromagnetic field distribution about the coaxial cable.
The conventional strain relief deforms the shape of the outer conductor and the dielectric material from their original geometry. When the dielectric material and outer conductor are deformed from their original geometry, the electromagnetic field distribution surrounding the coaxial cable is also changed. The modified electromagnetic field distribution created by the strain relief affects the coaxial cable""s impedance characteristics and may degrade signal performance. For example, the modified electromagnetic field distribution may increase the impedance exhibited by the coaxial cable and or may affect the voltage standing wave ratio (VSWR), shield effectiveness and the like.
An improved strain relief is needed that avoids the above noted problems and other disadvantages experienced heretofore.